Circular Countdown Timer

My toddler can't tell time or read a digital timer, but she understands if sands run out of an hourglass or a kitchen timer is circling back to zero. I'd like a circular countdown timer on my phone. Say she has a tantrum in a store, it's a 2-minute timeout. At the park, she has 15 minutes before we have to leave. At home, 20 minutes for TV. 30 minutes for storytime. Whatever.

I would like a circular, pie chart-like countdown timer. The user sets a duration and the app calculates it in 360 degrees.

As with the good timer apps, it would not let the Android device sleep.

A user should be able to set hours, minutes, even seconds.

Optionally, an alarm or notification would sound at the end.

Optionally, the background or circle color would change to yellow when 10% of the duration remains and red when, say, 2% remains. Another option would be to have the circle turn GREEN at the end of the cycle, as with timeouts ending.